Chang'an is in north central China.
Chang'an ([ʈʂʰǎŋ.án] ( listen); simplified Chinese: 长安; traditional Chinese: 長安) was an ancient capital of more than ten dynasties in Chinese history, today known as Xi'an. Chang'an means "Perpetual Peace" in Classical Chinese since it was a capital that was repeatedly used by new Chinese rulers. During the short-lived Xin dynasty, the city was renamed "Constant Peace" (Chinese: 常安; pinyin: Cháng'ān); yet after its fall in AD 23, the old name was restored. By the time of the Ming dynasty, a new walled city named Xi'an, meaning "Western Peace", was built at the Sui and Tang Dynasty city's site, which has remained its name to the present day.
Chang'an had been settled since Neolithic times, during which the Yangshao Culture was established in Banpo in the city's suburb. Also in the northern vicinity of the modern Xi'an, Qin Shi Huang of the Qin dynasty held his imperial court, and constructed his massive mausoleum guarded by the famed Terracotta Army.
From its capital at Xianyang, the Qin dynasty ruled a larger area than either of the preceding dynasties. The imperial city of Chang'an during the Han dynasty was located northwest of today's Xi'an. During the Tang dynasty, the area to be known as Chang'an included the area inside the Ming Xi'an fortification, plus some small areas to its east and west, and a major part of its southern suburbs. The Tang Chang'an hence, was 8 times the size of the Ming Xi'an, which was reconstructed upon the premise of the former imperial quarter of the Sui and Tang city. During its heyday, Chang'an was one of the largest and most populous cities in the world. Around AD 750, Chang'an was called a "million people's city" in Chinese records, while modern estimates put it at around 800,000–1,000,000 within city walls. According to the census in 742 recorded in the New Book of Tang, 362,921 families with 1,960,188 persons were counted in Jingzhao Fu (京兆府), the metropolitan area including small cities in the vicinity.